The present invention relates to a smart card payment system, and in particular to such a system with system-level monitoring of the stored value.
Smart card technology has enabled two consumer payment applications: the charge (credit or debit) card with enhanced security (especially in off-line payment,) and the stored-value card, also called electronic purse. The two applications are complementary: the charge card is more suitable for medium-to-higher payments, while the electronic purse's arena is small payments. The potential synergy between these two payment applications is described in a co-pending U.S. patent application Ser. No. 08/533,599 of Sep. 25, 1995, and in its equivalent PCT publication WO 96/09592, both by the present inventor.
A major concern in any payment system is security, i.e., preventing unauthorized transfer or production of money. In smart card stored-value payment, a vast number of patents, publications and implemented solutions deal with safeguarding payment and other value transfer transactions at the bank-to-consumer, consumer-to-merchant and merchant-to-bank levels. There are combinations of hardware, software and procedures believed to withstand any attack conducted for a reasonable time using known means. However, as security is so crucial to payment systems, many bankers insist on monitoring the flow of money at the system level, to reconfirm the flawless operation of the security means at the transaction levels. This security requirement has been commonly transformed into the concept of "full accountability", i.e. recording and reporting all single stored-value transactions to a central computer, for checking and confirming that each addition of value to a first stored-value device has occurred only as the same amount had been deducted from a second stored-value device. Such accountability schemes require an enormous amount of data storage and transfer and may interfere with the privacy of consumers carrying personal payment cards.